Large diameter lengths of pipe intended for use as vessels, tanks, or sections of a pipeline normally are cylindrical at the time they are manufactured. However, as such pipe lengths are stored, transported, or conditioned for welding to another length, it is more common than not that the pipe lengths will assume an oval configuration. If the lengths are to be welded together with as little mismatch between their confronting ends as is possible, therefore, the confronting ends of the pipe lengths must be reformed so that their configurations conform to one another. This has been done in the past by welding dogs or clips to the pipe sections adjacent their confronting ends so that wedges and the like can be used to effect relative adjustment of the ends. After two pipe lengths have been secured together, the dogs and clips are burned or ground off, but these practices are time consuming. They also are objectionable since heat stressing of the pipes is possible resulting in permanent damage thereto.
There also have been proposed various kinds of internal alignment clamps which may be fitted within one length of pipe in a position to span the joint between such pipe and another similar pipe. Such clamps are necessarily heavy, cumbersome units and require the expenditure of considerable effort and ingenuity in locating them in proper position relative to the joint between the two pipes. Further, such clamps usually have a gap in expanded condition which prevents full engagement between the clamp and the internal surfaces of the pipes, thereby providing for the possibility of misalignment at the zone of such gap or the discharge of weldment into the pipes through the gap.